The disclosures of the following references are incorporated herein by reference in their entirety:
U.S. Pat. No. 9,244,356
U.S. Pat. No. 8,492,189
US 2016/0345430 A1
CN 104992752 A
US 2016/0225483 A1
CN 103864062 B
WO 2011/046775 A1
Won-Kyung Kim et al., Cu Mesh for Flexible Transparent Conductive Electrodes, Scientific Reports 5, Jun. 3, 2015, Article number: 10715;
Chao Chen et al., Fabrication of silver nanowire transparent conductive films with an ultra-low haze and ultra-high uniformity and their application in transparent electronics, J Mater. Chem. C, 5, 31, Jan. 2017, pp. 2240-2246;
Zongping Chen et al., Three-dimensional flexible and conductive interconnected graphene networks grown by chemical vapour deposition, Nature Materials 10, 10 Apr. 2011, pp. 424-428;
Han, J.; Yuan, S.; Liu, L.; Qiu, X.; Gong, H.; Yang, X.; Li, C.; Hao, Y.; Cao, B., Fully indium-free flexible Ag nanowires/ZnO:F composite transparent conductive electrodes with high haze, J. Mater. Chem. A 2015, 3, pp. 5375-5384;
Pei, Z. L.; Zhang, X. B.; Zhang, G. P.; Gong, J.; Sun, C.; Huang, R. F.; Wen, L. S., Transparent conductive ZnO:Al thin films deposited on flexible substrates prepared by direct current magnetron sputtering. Thin solid Films 2006, 497, 20-23;
Chen, Y. Z.; Medina, H.; Tsai, H. W.; Wang, Y. C.; Yen, Y. T.; Manikandan, A.; Chueh, Y. L. Low Temperature Growth of Graphene on Glass by Carbon-Enclosed Chemical Vapor Deposition Process and Its Application as Transparent Electrode. Chem. Mater. 2015, 27, 1636-1655;
Liu, Z.; Parvez, K.; Li, R.; Dong, R.; Feng, X.; Mullen, K. Transparent Conductive Electrodes from Graphene/PEDOT:PSS Hybrid Inks for Ultrathin Organic Photodetectors. Adv. Mater. 2015, 27, 669-675;
Lipomi, D. J.; Lee, J. A.; Vosgueritchian, M.; Tee, C. K.; Bolander, J. A.; Bao, Z. Electronic Properties of Transparent Conductive Films of PEDOT:PSS on Stretchable Substrates. Chem. Mater. 2012, 24, 373-382;
Wu, H.; Kong, D.; Ruan, Z.; Hsu, P. C.; Wang, S.; Yu, Z.; Carney, T. J.; Hu, L.; Fan, S.; Cui, Y. A transparent electrode based on a metal nanotrough network. Nat. Nanotechnol. 2013, 8, 421-425.
In a US patent under the patent number U.S. Pat. No. 8,492,189, a combinatorial or a two-step method for depositing transparent conductive oxide on a substrate, annealing and etching the same for improving the uniformity and initial texture of thin film photovoltaic solar cell is provided. However, notwithstanding the combinatorial or the two-step method, a relatively high annealing temperature is still required in that patent, which is greater than 200° C. Because PVD is employed for the deposition process, the cost on maintaining a constant temperature at such a relatively high level is still high.
In a US patent under the patent number U.S. Pat. No. 9,244,356, a method of using roll mask lithography (RML) to fabricate metal mesh structures is provided, where in certain embodiments a photoresist layer is deposited on a metal layer and patterned followed by etching to remove the metals exposed by openings. The metal mesh structure is formed after removing the photoresist. Other embodiments in that patent provide formation of metal mesh structure by depositing the metal materials onto a template that may be formed by coating a photoresist layer on a substrate followed by patterning using RML such that no etching is required. Either way cannot create a metal mesh structure that is partially integrated into the substrate while the remaining part is not but exposed out of the substrate for contacting with any potential external structure.
In a US patent application under the publication number US 2016/0225483 A1, a transparent conductive film comprising a transparent polymer that allows silver nanowires to partially dispersed therein was disclosed. Fused latex polymer particles were used to fuse with the interacted nanowires such that those embedded in the fused latex polymer retain excellent wire-to-wire contact while the rest of the nanowire not being embedded in the fused latex polymer has an improved conductivity. However, the fused latex polymer is not configured to embed nanowires with high aspect ratio. Also, the nanowires exposed outside the fused latex polymer are not in regular pattern or desired orientation because they are dispersed into the fused latex polymer particles.
In another US patent application under the publication number US 2016/0345430 A1, a transparent conductive film with a metal mesh embedded in a substrate and a method of fabrication thereof is provided, where the metal mesh has a cap that is pressed and embedded in a substrate or a deformable material on a substrate, providing superior mechanical stability by mechanical interlocking. Therefore, when the substrate is bent, the cap helps anchor the metal mesh in the substrate, keeping the metal mesh securely fastened and helping to improve its mechanical strength and stability. The fabrication method is vacuum-free, where the metal mesh is tapered in a direction that is opposite to the cap, and one surface of the resulting metal mesh is flush with the substrate surface. One problem of using that method arises from the additional cap which is required for the metal mesh to anchor in the substrate during bending. Because during the thermal imprinting or transfer from one substrate to the other, the cap of the metal mesh would make the surface of the substrate uneven when pressure is exerted from two platens of the hot press.
Consequently, there is an unmet need to have a transparent conductive thin film that has physical stability while flexibility to be further patterned or interact with any external structure without losing its optical, electrical and mechanical properties.